1. Field of the Invention
The instant disclosure relates to a solid electrolytic capacitor; in particular, a solid electrolytic capacitor with a protective structure and a method for manufacturing thereof.
2. Description of the Related Art
Referring to FIG. 1, which shows a conventional solid electrolytic capacitor 10 consists of stacked capacitor elements 6. FIG. 2 shows a separate capacitor element 6 of the conventional solid electrolytic capacitor of FIG. 1. Particularly, each capacitor element 6 has an anode portion 7 and a cathode portion 8. The bodies of the capacitors are placed on top of one another in a stack-configuration while the anodes connected to a positive terminal 12 and the cathodes connected to a negative terminal 13. Conventionally, the portions of the capacitor elements 6 are joined by conductive adhesives (shown as layer 18 in FIG. 1), and a synthetic resin material 14 is applied directly to cover the capacitor elements 6. Thus, the anode, the cathode, and the stacked capacitor elements form the main body of the capacitor unit. Furthermore, with the exception of the bottom surface of the positive and negative terminals 12 and 13, the synthetic resin material 14 substantially covers the upper surface of the capacitor structure to form the capacitor package.
Each capacitor element 6 is made of a dielectric oxide film 2 and a cathode layer 3 forming over an aluminum foil 1. Specifically, the cathode layer 3 comprises solid electrolytic layer 3a, which is created from a conductive polymer known as polythiophene; a carbon layer 3b, and a silver coating 3c. The section where the cathode layer 3 forms over the dielectric oxide film 2 defines a cathode region 8. On the other hand, the section without the cathode layer 3 defines an anode region 7. When stacking the capacitor element 6, soldering (anode welding) is performed between the neighboring anode regions 7. In addition, a conductive adhesive 18 is used between the neighboring cathode regions 8 of the capacitor element 6. Thus, the stacked solid electrolytic capacitor 10 is formed.
A first and a second groove 16 and 17 are disposed near the border region 15 between the cathode region 8 and the anode region. The anode region 7 may be easier bent at the first groove 16 and the second groove 17. The first groove 16 and the second groove 17 act to reduce the bending stress around the border 15 between the anode region 7 and the cathode region 8. However, during the manufacturing process of the capacitor, especially during the application of the synthetic resin 14, a large force is usually applied for molding and shaping of the resin structure. Thus, the large force applied during the manufacturing process may damage the capacitor element 6 easily. Moreover, the structural damage may cause short-circuit and excessive current leakage of the capacitor unit. Therefore, heavy emphasis has been placed on protecting the capacitors during the manufacturing process.